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  • Surface phase diagrams of pristine and hydroxylated barium hexaferrite surfaces from first-principles atomistic thermodynamics [Elektronski vir]
    Poberžnik, Matic, kemik ...
    Barium hexaferrite (BHF) is a ferrimagnet, whose hexagonal unit cell presents five iron crystallographic sites along the  -axis. At the nanoscale, BHF nanoparticles grow in the form of platelets, ... characterized by a low thickness along its principal magnetization axis ( -axis), displaying uniaxial magnetic anisotropy with the easy axis pointing perpendicular to the platelet. This unique property of BHF nanoplatelets has lead to a variety of novel applications, which often require surface functionalization. However, it has been observed that the nanoplatelets display two different surface morphologies depending on the stage/conditions of preparation. To ground these experimental observations, we employ the ab initio thermodynamics framework to perform a systematic investigation of the thermodynamic stability of BHF bulk terminations under a wide range of chemical conditions. We calculate the surface phase diagrams of pristine and hydroxylated bulk terminations along the  -axis. For pristine terminations, two different iron terminated surfaces are preferred: the barium containing 2b termination (Ba-rich conditions) and the 4f iron terminated surface (Ba-poor conditions). In the presence of water, the hydroxylated oxygen-terminated surfaces (12k-O) are identified as the most stable ones at Ba-poor conditions and low pH values, whereas the hydroxylated 2b surface is preferred at high pH and Ba-rich conditions.
    Source: Applied surface science [Elektronski vir]. - ISSN 1873-5584 (Vol. 637, [article no.] 157890, 2023, str. 1-12)
    Type of material - e-article ; adult, serious
    Publish date - 2023
    Language - english
    COBISS.SI-ID - 157316867

    Link(s):

    https://www.sciencedirect.com/science/article/pii/S0169433223015696?via%3Dihub
    DOI

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